It is desirable to provide an echo cancellation technique that enables an environmental change to be flexibly addressed. Provided is a signal processing apparatus including: an echo cancellation unit that learns an estimated transfer characteristic in a space through which a signal reproduced by a speaker is input to a microphone, and performs echo cancellation on the basis of the estimated transfer characteristic learned; and an environmental change detection unit that detects an environmental change, in which the echo cancellation unit learns the estimated transfer characteristic by causing the speaker to reproduce a sound for learning on the basis of detection of the environmental change.